The history of the atom

• What did John Dalton describe atoms as?


  Solid spheres which comprised the different elements
• Who created the plum pudding model?


  J.J. Thomson
• What is the plum pudding model?


  The idea that the atom was composed of positive and negative charges scattered throughout, similar to plums in a pudding.
• What model did Rutherford and Marsden make?


  Gold foil experiment
• What conclusion did Rutherford and Marsden reach from their gold foil test?


  Most of the atom is empty space.
• What model did Rutherford come up with after the foil experiment?


  Nuclear model
• What idea did Niels Bohr propose?

  The idea that electrons were contained in fixed shells which orbit the nucleus
• Further experiments by Rutherford and others showed that the nucleus can be divided into smaller particles with the same charge as the hydrogen nucleus, called protons.
• What did James Chadwick discover?


  The neutron.